BRUSSELS -- European Union foreign-policy chief Catherine Ashton has called on Western negotiators to be "determined and creative" in their discussions with Tehran on Iran's nuclear program.

Speaking on March 16 at the German Marshall Fund's Brussels Forum, Ashton said negotiators had to do more to build a level of "communication" and "trust" with the Iranian side.

Such a move, she said, would encourage Iranian officials already beginning to engage in a "real discussion" about concerns they are using their program to build an arsenal of nuclear weapons.

"When I first started to lead these negotiations, we weren't really discussing the subject. Now we discuss the subject in detail, we have the slideshow presentations, we have a real discussion about the issues both when the technical-level discussions take place and the political-level," Ashton said.

Iran, which is successfully producing enriched uranium at two facilities, says its nuclear program is for civilian purposes only.

The United States and the EU have imposed a series of economic sanctions on Iran, including limitations on imports of Iranian crude oil, to cut off funding for Tehran's nuclear program.

High-level talks on the issue between Iran and the United States, Russia, France, China, Britain, and Germany are set to resume in early April.

Serbia-Kosovo Talks

Ashton also addressed ongoing negotiations between Balkan neighbors Serbia and Kosovo about normalizing ties five years after Pristina declared independence from Belgrade.

Ashton, who last week mediated talks in Brussels between Serbian and Kosovar Prime Ministers Ivica Dacic and Hashim Thaci, said she believed it is "possible" for Serbia and Kosovo to agree on normalizing ties, but only if they can resolve "difficult problems" still dividing the two sides.

"Whether they will or not will depend on whether we can find a way through some of the difficult problems they have," Ashton said. "But I have met with members of the government in Pristina and I have met with the opposition parties and there is, I think, a genuine willingness to achieve this. I'll do my very best to see if we can."

Ashton's comments followed a brief visit to Kosovo, where she met with both members of the government in Pristina as well as opposition parties.

Serbia is calling on Pristina to grant greater autonomy to ethnic Serbs living in northern Kosovo, while Kosovo wants Serbia to recognize its independence.

Progress in negotiations could potentially open the door to EU accession talks with Serbia.

Ashton is due to advise the EU Council of Ministers on whether the EU should launch such talks ahead of a fresh round of talks between Thaci and Dacic in Brussels on March 20.